Multi-edge folded louvered fin for heat exchanger

ABSTRACT

A multi-edge folded louvered fin for a heat exchanger includes a blank extending longitudinally having a longitudinal axis and folded in a serpentine configuration having top and bottom base portions and a fin body extending between adjacent ones of said top and bottom base portions. The multi-edge folded louvered fin also includes a plurality of louvers for each fin body extending outwardly at a first predetermined angle relative to a direction of air flow entering the heat exchanger. Each of the louvers has a leading edge and a trailing edge being offset longitudinally relative to each other. The multi-edge folded louvered fin includes the fin body being disposed at a second predetermined angle relative to the direction of air flow entering the heat exchanger. The multi-edge folded louvered fin further includes the first predetermined angle opposing the second predetermined angle.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a multi-edge folded louvered fin for a heat exchanger in a motor vehicle.

[0003] 2. Description of the Related Art

[0004] It is known to provide a louvered fin for use in a heat exchanger such as an evaporator in a motor vehicle. An example of such a louvered fin is disclosed in U.S. Pat. No. 5,501,270 to Young et al. In that patent, the louvered fin typically includes a generally planar base having a longitudinal axis generally perpendicular to the direction of air flow entering the heat exchanger and a transverse axis generally parallel to the direction of air flow. The axes define a main plane disposed at a predetermined angle relative to the direction of air flow entering the heat exchanger. The louvered fin also has a plurality of apertures for receiving tubes therethrough and a plurality of louvers disposed on the base extending generally parallel to the longitudinal axis of the base. The predetermined angle can be between 140 and 175 degrees to the direction of air flow entering the heat exchanger. However, the louvers are placed at a zero degree (0°) angle of attack relative to the air flow.

[0005] Another known fin for a heat exchanger such as an evaporator is disclosed in U.S. Pat. No. 5,505,257 to Goetz, Jr. In this patent, a corrugated fin strip for a heat exchanger has interfacing parallelogram shaped fin panels joined by successive parallel crests, all fin panels having the same parallelogram shape selected in accordance with a desired configuration of the heat exchanger. In one embodiment, the parallel crests extend obliquely between the longitudinal edges of a rectilinear metal strip from which the fin strip is formed, and are adapted to be alternatively attached to the flat face of a heat exchanger tube in oblique relation to parallel sides of the tube, thereby defining an air flow direction oblique to the length thereof. However, the fin lacks louvers for turning the air flow to maximize heat transfer.

[0006] Another known fin for a heat exchanger such as a condenser is disclosed in U.S. Pat. No. 6,247,527 to Paulman. In this patent, an improved fin array is an elongated one-piece fin member having top and bottom base portions with fin sets extending between adjacent top and bottom base portions. The top and bottom base portions are generally flat for bonding to the heat exchanger tubes. Each fin set includes a plurality of individual fins extending generally perpendicular to a longitudinal length of the fin member and having side edges that are longitudinally offset with respect to each other. The offset fin edges provide increased air flow over the individual fins. However, this fin does not maximize heat transfer relative to pressure loss.

[0007] Although the above fins have worked for a heat exchanger, it is desirable to provide a louvered fin for a heat exchanger that maximizes heat transfer relative to pressure loss. It is also desirable to provide a multi-edge folded fin for a heat exchanger that has a minimum drop in airside pressure for increased heat transfer. Therefore, there is a need in the art to provide a multi-edge folded louvered fin for a heat exchanger that outperforms conventional louvered fins in both heat transfer and air pressure drop.

SUMMARY OF THE INVENTION

[0008] Accordingly, the present invention is a multi-edge louvered fin for a heat exchanger including a blank extending longitudinally having a longitudinal axis and folded in a serpentine configuration having top and bottom base portions and a fin body extending between adjacent ones of said top and bottom base portions. The multi-edge folded louvered fin also includes a plurality of louvers for each fin body extending outwardly at a first predetermined angle relative to a direction of air flow entering the heat exchanger. Each of the louvers has a leading edge and a trailing edge being offset longitudinally relative to each other. The multi-edge folded louvered fin includes the fin body being disposed at a second predetermined angle relative to the direction of air flow entering the heat exchanger. The multi-edge folded louvered fin further includes the first predetermined angle opposing the second predetermined angle.

[0009] One advantage of the present invention is that a multi-edge folded louvered fin for a heat exchanger such as an evaporator is provided for a motor vehicle. Another advantage of the present invention is that the multi-edge folded louvered fin has a small angle on the fin body and an opposing angle on the louvers to maximize heat transfer relative to pressure loss. Yet another advantage of the present invention is that the multi-edge folded louvered is provided for a heat exchanger that has a minimum drop in airside pressure for increased heat transfer.

[0010] Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a multi-edge folded louvered fin, according to the present invention, illustrated in operational relationship with a heat exchanger.

[0012]FIG. 2 is a perspective view of a blank gathered into finished geometry for the multi-edge folded louvered fin of FIG. 1 illustrating folds thereof.

[0013]FIG. 3 is a top view of the multi-edge folded louvered fin of FIG. 1.

[0014]FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.

[0015]FIG. 5 is an enlarged side view of the multi-edge folded louvered fin of FIG. 1.

[0016]FIG. 6 is a sectional view taken along line 6-6 of FIG. 5.

[0017]FIG. 7 is an enlarged view of a portion in circle 7 of the multi-edge folded louvered fin of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0018] Referring to the drawings and in particular FIG. 1, one embodiment of a heat exchanger 10, such as an evaporator, is shown for a motor vehicle (not shown). The heat exchanger 10 includes a plurality of generally parallel-elongated tubes 12 and a header 14 connected to each end of the tubes 12. The heat exchanger 10 includes a fluid inlet 16 for conducting cooling fluid into the heat exchanger 10 formed in one of the headers 14 and a fluid outlet 18 for directing fluid out of the heat exchanger 10 formed in the other header 14. The heat exchanger 10 also includes a plurality of spacers or multi-edge folded louvered fins, generally indicated at 20 and according to the present invention, attached an exterior of each of the tubes 12. The multi-edge folded louvered fins 20 are disposed between each of the tubes 12. The multi-edge folded louvered fins 20 serve as a means for conducting heat away from the tubes 12 while providing additional surface area for convective heat transfer by air flowing over the heat exchanger 10. It should be appreciated that, except for the multi-edge folded louvered fins 20, the heat exchanger 10 is conventional and known in the art. It should also be appreciated that the multi-edge folded louvered fins 20 could be used for heat exchangers in other applications besides motor vehicles.

[0019] Referring to FIGS. 2 through 7, the multi-edge folded louvered fin 20 starts as a blank 22. The blank 22 is generally planar and rectangular shape. The blank 22 extends longitudinally having a longitudinal axis. The blank 22 is made of a metal material commonly aluminum or copper. The blank 22 is folded in a serpentine pattern of alternating top and bottom base portions 24 and 26, respectively. A plurality of fin bodies 28 is formed in the blank 22 extending between and connecting adjacent ones of the top and bottom base portions 24 and 26. The term “fin body or fin bodies” as used herein is defined by a centerline through a bank or set of louvers 30 to be described. The fin bodies 28 are disposed at a predetermined angle to be described relative to a direction of air flow entering the heat exchanger 10. Each of the fin bodies 28 includes a plurality of louvers 30 extending outwardly. Each louver 30 is positioned at a predetermined louver angle of approximately positive five degrees (5°) to approximately positive fifteen degrees (15°) relative to the airflow while each fin body 28 is positioned at a predetermined fin body angle of approximately negative five degrees (5°) to approximately negative fifteen degrees (15°) relative to the airflow. The louvers 30 are generally planar and rectangular in shape. The louvers 30 extend longitudinally or generally parallel to a longitudinal axis of the blank 22. The louvers 30 are cut or lanced and bent out of the blank 22 to form apertures 32 for air to flow therebetween. The louvers 30 are spaced laterally at a relatively small or predetermined louver pitch such as 0.8 millimeters (mm) to 1.0 mm to enhance heat transfer. It should be appreciated that the included angle between the louver 30 and fin body 28 is approximately ten degrees (10°) to approximately thirty degrees (30°). It should also be appreciated that the louvers 30 enhance heat transfer performance. It should further be appreciated that the top and bottom base portions 24 and 26 are brazed to the tubes 12.

[0020] Referring to FIGS. 2 and 5, each of the louvers 30 has a leading edge 34 and a trailing edge 36 longitudinally offset with respect to the leading edges 34 and trailing edges 36 of all of the other louvers 30 in a fin body 28. The offset positioning of the louvers 30 maximizes heat transfer of the louvers 30 with the ambient air because the offset leading and trailing edges 34 and 36 provide maximum exposure to the air and the louvers 30 do not block air with respect to each other. It should be appreciated that for maximum heat transfer efficiency the louvers 30 should not be parallel to the on-coming air stream.

[0021] As illustrated in FIG. 4, each of the louvers 30 on each of the fin bodies 28 is disposed at a predetermined angle, Φ, of between approximately five (+5°) to approximately fifteen positive degrees (+15°) relative to the direction of the air flow A or oncoming air stream entering a front face of the heat exchanger 10. In addition, each fin body 28 is disposed at an angle θ of between approximately five (−5°) to approximately fifteen negative degrees (−15°) relative to the direction of the air flow A or oncoming air stream entering a front face of the heat exchanger 10. It should be appreciated that the included angle between the louver 30 and fin body 28 is approximately ten degrees (10°) to approximately thirty degrees (30°). It should also be appreciated that by placing the fin bodies 28 at an angle to the oncoming air stream results in low pressure losses and air flow passes between each of the louvers 30 very easily, increasing the number of louvers 30 contacted by the air stream, thereby increasing the overall effectiveness of the heat exchanger 10 while decreasing the pressure building across the heat exchanger 10. It should further be appreciated that the angle of the louvers 30 opposes the angle on the fin bodies 28, thereby maximizing heat transfer relative to pressure loss.

[0022] The multi-edge folded louvered fin 20 is formed as a monolithic structure being integral, unitary, and one-piece. The multi-edge folded louvered fin 20 is formed by a conventional roll forming process as disclosed in U.S. Pat. No. 6,247,527, the disclosure of which is hereby incorporated by reference to form the blank 22 into a corrugated or folded style of a typical louvered fin as illustrated in FIG. 2.

[0023] The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.

[0024] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described. 

What is claimed is:
 1. A multi-edge folded louvered fin for a heat exchanger comprising: a blank extending longitudinally having a longitudinal axis and folded in a serpentine configuration having top and bottom base portions and a fin body extending between adjacent ones of said top and bottom base portions; a plurality of louvers for each said fin body extending outwardly at a first predetermined angle relative to a direction of air flow entering the heat exchanger, each of said louvers having a leading edge and a trailing edge being longitudinally offset with respect to each other; said fin body being disposed at a second predetermined angle relative to the direction of air flow entering the heat exchanger; and said first predetermined angle opposing said second predetermined angle.
 2. A multi-edge folded louvered fin as set forth in claim 1 wherein said blank is generally planar and rectangular in shape.
 3. A multi-edge folded louvered fin as set forth in claim 1 wherein said fin body includes a plurality of apertures extending therethrough, one of said apertures being disposed between an adjacent pair of said louvers for air to flow therebetween.
 4. A multi-edge folded louvered fin as set forth in claim 1 wherein said first predetermined angle is from five degrees to fifteen degrees.
 5. A multi-edge folded louvered fin as set forth in claim 1 wherein said second predetermined angle is from five degrees to fifteen degrees.
 6. A multi-edge folded louvered fin as set forth in claim 1 wherein said blank is folded in corrugations.
 7. A multi-edge folded louvered fin as set forth in claim 1 wherein said fin is integral, unitary, and formed as one-piece.
 8. A multi-edge folded louvered fin for a heat exchanger comprising: a blank extending longitudinally having a longitudinal axis and folded in a serpentine configuration having top and bottom base portions and a fin body extending between adjacent ones of said top and bottom base portions; a plurality of louvers for each said fin body extending outwardly at a first predetermined angle relative to a direction of air flow entering the heat exchanger, each of said louvers extending in a direction parallel to the longitudinal axis and being spaced laterally and having a leading edge and a trailing edge being longitudinally offset with respect to each other; said fin body being disposed at a second predetermined angle relative to the direction of air flow entering the heat exchanger; and said first predetermined angle opposing said second predetermined angle.
 9. A multi-edge folded louvered fin as set forth in claim 8 wherein said blank is generally planar and rectangular in shape.
 10. A multi-edge folded louvered fin as set forth in claim 8 wherein said first predetermined angle is from positive five degrees to positive fifteen degrees.
 11. A multi-edge folded louvered fin as set forth in claim 8 wherein said second predetermined angle is from negative five degrees to negative fifteen degrees.
 12. A multi-edge folded louvered fin as set forth in claim 8 wherein said blank is folded in corrugations.
 13. A multi-edge folded louvered fin as set forth in claim 8 wherein said fin is integral, unitary, and formed as one-piece.
 14. A multi-edge folded louvered fin as set forth in claim 8 wherein said blank is made of a metal material.
 15. A heat exchanger comprising: a plurality of tubes; a plurality of multi-edge folded louvered fins disposed between each of said tubes; and each of said multi-edge folded louvered fins comprising a blank extending longitudinally having a longitudinal axis and folded in a serpentine configuration having top and bottom base portions and a fin body extending between adjacent ones of said top and bottom base portions, a plurality of louvers for each said fin body extending outwardly at a first predetermined angle relative to a direction of air flow entering the heat exchanger, each of said louvers having a leading edge and a trailing edge being longitudinally offset with respect to each other, said fin body being disposed at a second predetermined angle relative to the direction of air flow entering the heat exchanger, and said first predetermined angle opposing said second predetermined angle. 